In the continuous casting of metals, such as aluminum and alloys thereof, the molten metal is poured into a mold having sidewalls and a starting block or wall which moves away from the sidewalls during casting. When molten metal is flowed into the mold, it rapidly solidifies from the effect of a coolant, usually water, which is, for instance, continuously sprayed on the exterior of the sidewalls. The starting block is moved away from the mold at a rate commensurate with the introduction of molten metal into the mold. Concurrently, a lubricant is continuously supplied to the interior sidewall surfaces of the mold to enhance movement of the solidified ingot with the starting block. Thus, a long ingot of metal is continuously produced.
In a method of providing the lubricant, such as oil, a continuous groove is cut in the end of the mold around the mold opening to function as a reservoir for the oil. A plurality of slots are cut in the mold from the oil groove to the mold interior, and oil from the groove flows through the slots and onto the interior mold surface. A cover plate, the oil ring, is fastened to the end of the mold over the oil reservoir groove in order to retain the oil therein. The inside dimensions of the oil ring are critical to insure that its assembly with the mold is suitable to enable lubrication of the mold and not interfere with the casting of the ingot. Typically, the metal first solidifies at the inner periphery of the oil ring and subsequently slides along the interior sidewall surfaces of the mold.
Examples showing oil rings situated as they are used in continuous casting are provided by U.S. Pat. Nos. 3,381,741 and 4,699,200, which are incorporated here by reference. The oil ring is designated "insert 22" and "insert 58" in U.S. Pat. No. 3,381,741 and "oil ring 30" in U.S. Pat. No. 4,699,200.
In the continuous casting of aluminum alloys, state of the art before the present invention has been to manufacture aluminum oil rings from aluminum alloys 3003 and 5052 (aluminum alloys mentioned herein, such as aluminum alloys 3003 and 5052, are as defined in the "Registration Record of Aluminum Association Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys", the Aluminum Association, Washington, D.C.).
It is also known to use copper oil rings for the continuous casting of aluminum alloys.